Among the conventionally-known types of power generators for application to cogeneration is the engine-driven type, and one example of such an engine-driven type power generator is disclosed in Japanese Patent Application Laid-open Publication No. HEI-11-200951A.
FIG. 6 hereof is a view explanatory of a fundamental construction of the engine-driven power generation apparatus for cogeneration disclosed in the HEI-11-200951A publication. This engine-driven power generation apparatus 100 includes, within a housing 101, a power generator 102, an engine 103 connected with the power generator 102 to drive the power generator 102, a ventilation fan 104 disposed above the engine 103, and a motor 105 connected with the ventilation fan 104 to drive the fan 104.
In the housing 101 are formed: an external air take-in hole 107 for taking in external air into the housing 101 for cooling the engine 103 and motor 105; a motor cooling air take-in hole 108 for taking in and directing part of the external air, taken in through the external air take-in hole 107, to and along the motor 105 to cool the motor 105; a motor cooling air discharge hole 109 for discharging the air taken in through the motor cooling air take-in hole 108 after cooling the motor 105; and an air discharge hole 111 for not only discharging the air discharged through the motor cooling air discharge hole 109 to outside of the housing 101 but also discharging the air, taken in through the external air take-in hole 107 and passed along an outer peripheral portion of the engine 103, to outside of the housing 101.
In the engine-driven power generation apparatus 100, the power generator 102 is driven by the engine 103 to generate electric power. The power generator 102 and engine 103 would produce heat during the power generation, and thus, there arises a need to cool the power generator 102 and engine 103 by discharging the heat to outside of the housing 101.
To cool the power generator 102 and engine 103 in the engine-driven power generation apparatus 100, the ventilation fan 104 is driven. By the ventilation fan 104 being driven, a negative pressure is produced within the housing 101, so that external air is taken, through the external air take-in hole 107, into the housing 101 as indicated by arrows (1) and (2) in FIG. 6. Most part of the taken-in air passes along the power generator 102 and engine 103 as indicated by arrows (3) and (5) and is then discharged, via the ventilation fan 104, to outside of the housing 101 through the air discharge hole 111.
In the aforementioned manner, a convection flow of air is produced within the housing 101, so that heat produced from the power generator 102 and engine 103 is discharged to outside of the housing 101. Further, the motor 105, which is a drive source for the ventilation fan 104, too would produce heat as it drives the ventilation fan 104. Cooling of the motor 105 too is effected by the external air taken through the external air take-in hole 107. Namely, part of the external air taken through the external air take-in hole 107 is directed through the motor cooling air take-in hole 108 to pass along a cooling air passageway 112 and then discharged through the motor cooling air discharge hole 109 together with the head produced from the motor 105.
However, the power generation apparatus 100 disclosed in the No. HEI-11-200951 publication requires a great number of component parts and hence high manufacturing cost, because it calls for the ventilation fan 104 for producing the negative pressure, the motor 105 for driving the ventilation fan 104 and the cooling air passageway 112 for passage therealong the air for cooling the motor 105.